The present invention relates to a novel polymeric compound having sustained anti-tumor activity and a method for the preparation thereof. More particularly, the invention relates to a polymeric compound with a polymeric backbone structure and pendant groups thereon having anti-tumor activity, which can be sustainedly released to exhibit the desired activity after administration.
As is known, several classes of organic compounds have anti-tumor or anti-cancer activity including, for example, nucleic acid derivatives and certain kinds of antibiotics. Among them, remarkable anti-tumor effects are obtained and clinical treatment is widely undertaken with 1-.beta.-D-arabinofuranosylcytosine against leukemia and with 5-fluorouracil and related compounds against solid tumors as the examples of the former class and anthracycline-type antibiotics, e.g. adriamycin and daunomycin, against acute leukemia and children's cancer as the examples of the latter class.
Along with the excellent anti-tumor activity, unfortunately, these known anti-tumor agents exhibit strong toxicity also to normal cells and various undesirable side effects are unavoidable in the administration of them to patients. For example, the anthracycline-type antibiotics cause decrease in the leukocytes and blood platelets, hepatopathy and other side effects. Therefore, clinical administration of these anti-tumor agents must be performed under more than sufficient caution against possible side effects so that the anti-tumor agent is usually administrated many times in small portions of dose bit by bit in a generally accepted therapeutic practice. Such a way of administration of a medicament is of course very troublesome and it is eagerly desired to develop an anti-tumor agent which can be administrated less frequently to a patient with no apprehension of the side effects.